1. Field of the Invention
The present invention relates to a die bonding method and apparatus.
2. Prior Art
When a plurality of dies are to be bonded to a substrate or tape (herein after collectively referred to as a xe2x80x9ctapexe2x80x9d), if the bonding portions of the tape have bad portions, bad dies are bonded to these bad bonding portions. The reason for this is as follows: if there are bonding portions to which dies are not bonded, a uniform flow of the molding in subsequent processes following bonding is not performed, so that strain is generated in the tape after molding; accordingly, good dies are bonded to good bonding portions on the tape, and bad dies are bonded to bad bonding portions on the tape.
In conventional die bonding methods, a judgement of good/bad of status of tape is made immediately before the tape that has been conveyed to a bonding position is subjected to the bonding operation. Meanwhile, a wafer and tray that accommodates bad dies are installed in a semiconductor chip supply section. Then, for good bonding portions on the tape, good dies on the wafer are picked up, transferred to the bonding position and bonded; while for bad bonding portions on the tape, bad dies are picked up from the tray, transferred to the bonding position and bonded. In other words, only good dies are picked up from the wafer and bonded. Bad dies on the wafer are not used; and instead, only bad dies in the tray are used and bonded.
In the above prior art, bad dies remaining on the wafer need to be removed manually and packed in the tray. Furthermore, an extra number of bad dies must be prepared in advance in the tray; and as a result, bad dies may sometimes be wasted.
Accordingly, the object of the present invention is to provide a die bonding method and apparatus in which bad dies that are to be removed from a wafer and packed in a tray are eliminated or minimized, in which there is no need to pack an unnecessarily large number of bad dies in a tray, and in which bad dies are used without any waste.
The above object is accomplished by a unique steps of the present invention for a die bonding method in which good dies are bonded to good bonding portions on a substrate or tape (collectively called a xe2x80x9ctapexe2x80x9d) and bad dies are bonded to bad bonding portions on this tape; and in the present invention, dies are classified into good dies and bad dies based upon the results of successive detection and discrimination of dies on a wafer by a detection means, the dies are registered on a wafer good/bad status map, and the dies registered on the wafer good/bad status map are picked up, transferred and bonded depending upon whether the dies required from the bonding portions on the tape are good or bad. In other words, dies registered on the wafer good/bad status map are picked up in response to a request for either good dies or bad dies depending upon the result of detection of the bonding portions on the tape, and then such dies are transferred and bonded to the bonding portions.
The above object is accomplished by another unique steps of the present invention for a die bonding method in which good dies are bonded to good bonding portions on a substrate or tape (collectively called a xe2x80x9ctapexe2x80x9d) and bad dies are bonded to bad bonding portions on this tape; and in the present invention: a tray which accommodates bad dies is provided in addition to a wafer; dies are classified into good dies and bad dies on the basis of the results of successive detection and discrimination of dies on a wafer by a detection means; dies are registered on a wafer good/bad status map; the dies registered on the wafer good/bad status map are picked up, transferred and bonded depending upon whether the dies required from the bonding portions on the tape are good or bad; and in a case where there are no bad dies registered on the wafer good/bad status map, then bad dies inside the tray are picked up, transferred and bonded. In other words, dies registered on the wafer good/bad status map are picked up in response to a request for either good dies or bad dies depending upon the result of detection of the bonding portions of the tape, and then such picked-up dies are transferred and bonded to the bonding portions; however, in a case where there are no bad dies registered on the wafer good/bad status map, then bad dies inside the tray are picked up, transferred and then bonded to the bonding portions.
The above object is further accomplished by a unique structure for a die bonding apparatus in which good dies are bonded to good bonding portions on a substrate or tape (collectively called a xe2x80x9ctapexe2x80x9d) and bad dies are bonded to bad bonding portions on this tape; and in the present invention the bonding apparatus includes:
a wafer ring holding device which positions and holds a wafer; a die transferring nozzle which picks up, holds and transfers dies from the wafer; a die detecting camera which detects the positions and good/bad status of the dies on the wafer; a tray which accommodates bad dies; a bad die chucking nozzle which picks up, holds and transfers bad dies from the tray; a tape conveying device which conveys the tape; a bonding device which bonds the dies to the bonding portions on the tape; and a bonding portion detecting camera which detects the good/bad status of the bonding portions on the tape; wherein
when good dies are to be bonded to good bonding portions on the tape, good dies from the wafer are picked up, transferred and bonded to the good bonding portions; and
when bad dies are to be bonded to bad bonding portions on the tape,
bad dies from the wafer are picked up, transferred and bonded to the bad bonding portions in cases where bad dies that have been detected on the wafer and registered are available, and
bad dies from the tray are picked up, transferred and bonded to the bad bonding portions in cases where no registered bad dies are available on the wafer.